A touchstone for psychology research, the 1972 Stanford marshmallow experiment serves as a classic indication of the link between delayed gratification and success. In the experiment, children were given a marshmallow with the promise of a second marshmallow if they could put off eating it.

Now, researchers have revisited the marshmallow experiment, finding that willpower extends beyond will itself. Children waited about twice as long for that second marshmallow if they had reason to believe it would come, while those who suspected they may not receive a second marshmallow were more likely to succumb to their sugar cravings, according to a study published in November’s issue of Cognition.

Researchers divided a group of 28 children in half. Before children were given a marshmallow, they would encounter an adult. One group met with an adult who was unreliable, promising some fun art supplies that never appeared. The other group was given the promised art supplies.

When a marshmallow was placed in front of each child, the children in the reliable environment waited four times longer, on average, than the children in the unreliable environment, Slate reported.

“Being able to delay gratification — in this case to wait 15 difficult minutes to earn a second marshmallow — not only reflects a child’s capacity for self-control, it also reflects their belief about the practicality of waiting,” Celeste Kidd, a doctoral candidate in brain and cognitive sciences at the University of Rochester and lead author on the study, told the Washington Post. ”Delaying gratification is only the rational choice if the child believes a second marshmallow is likely to be delivered after a reasonably short delay.”

The researchers said this could be true on a larger scale, the Washington Post reported. Children who have lived in an environment in which promises are always broken and outcomes often unreliable, will naturally be prone to take what they can get without trusting in the promise of something more.

"Don't do the marshmallow test on your kitchen table and conclude something about your child," Kidd told CBS News. "It especially would not work with a parent because your child has all sorts of strong expectations about what a person who loves them very much is likely to do."